Non-Equilibrium Nano-Physics

Different observable features emerging around a localized spin moment adsorbed on a Rashba surface, as function of the energy. The localized spin undergoes a inelastic spin transition at 8 meV, which is seen as a step in the induced spin-polarization (a), solid lines, and in the topological number, dashed. (b) For energies below the onset of the inelastic scattering, the spin texture is in-plane (Q=0), whereas for energies that activates the inelastic scattering the spin texture also comprises an out-of-plane component (Q>0). (c) Inelastic electron tunneling spectroscopy measurements give a peak (bold) at the onset of the inelastic transition. Different orientation of the tip magnetic moment yield variations in the contrast since the spin-dependent component of the conductance derivative is sensitive to the magnetic configurations.

Research

The theme and focus is devoted to physical phenomena that happen under general non-equilibrium conditions, including time-dependence and strong perturbations, or distortions, under external force fields, e.g., voltage bias and thermal gradient. Our research can be very much partitioned into two branches.

The first branch constitute development of new theoretical framework for studies of dynamical aspects of correlated materials under non-equilibrium conditions. Here, the primary focus is on fundamental mechanisms for couplings between electronic and internal degrees of freedom, which may be of, e.g., magnetic, electric, and mechanical nature, and they may be coupled effectively through the electronic structure. It is crucial to deeply analyze the importance of those interactions in the bigger picture, since they may dramatically influence the physical dynamics.

The second branch concerns applications of our new developments to address properties of concrete systems, such as dynamical magnetic exchange interactions between magnetic molecules, electric and thermal field control of magnetic exchange interactions, vibrationally induced superconductivity in graphene and topological insulators, novel magnetic textures induced by vibrational defects in topological superconductors, remote control of dynamical quantum interference, among others.

Special attention is paid to phenomena that are currently being investigated by local probing techniques (scanning tunneling and atomic force microscopy/spectroscopy). Here we address issues related to the general theoretical description of the measurements but also physical origins of probe induced variations in, e.g., anisotropy fields.

Our work is supported by external grants from the Swedish Research Council and Stiftelsen Olle Engqvist Byggmästare.